<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        * {
            margin: 0;
            padding: 0;
            background-color: #000;
        }

        .main {
            width: 620px;
            height: 350px;
            margin: 60px auto;
            background-color: pink;
        }

        .main ul {
            width: 100%;
            display: flex;
            flex-wrap: wrap;
        }

        .main ul li {
            list-style: none;
            flex: 1;
            padding: 2px;
        }
    </style>
</head>

<body>
    <div class="main">
        <ul>
            <li><img src="./素材/01.jpg" alt=""></li>
            <li><img src="./素材/02.jpg" alt=""></li>
            <li><img src="./素材/03.jpg" alt=""></li>
            <li><img src="./素材/04.jpg" alt=""></li>
            <li><img src="./素材/05.jpg" alt=""></li>
            <li><img src="./素材/06.jpg" alt=""></li>
        </ul>
    </div>
</body>
<script src="https://cdn.staticfile.org/jquery/1.10.2/jquery.min.js"></script>
<script>
    $(function () {
        $('.main ul').find('li').mouseenter(function () {
            $(this).siblings('li').css('opacity', '0.4')
        })
        $('.main ul').find('li').mouseleave(function () {
            $(this).siblings('li').css('opacity', '1')
        })
    })
</script>

</html>